1. Field of the Invention
This invention relates to a hand held camera for exposing successive portions of the same light sensitive surface of a film unit.
2. Description of the Prior Art
Photographic apparatus for exposing successive portions of the same light sensitive surface of a film unit or of a predetermined area of a strip or reel of film are generally well known. One example of this type of photographic apparatus is a camera having a movable frame for supporting a predetermined area of a roll of film beneath a fixed lens system which focuses an image of a subject onto a discrete portion or exposure frame of the predetermined area of the film. After the discrete portion has been exposed, the movable frame is automatically indexed one position laterally so that a new unexposed discrete portion of the film is brought into position for exposure by the lens system. This portion of the film is then exposed and the movable frame is again automatically indexed or shifted one position laterally so that another unexposed portion is brought into position for exposure. This sequence of steps is repeated across the width of the film until a complete row of frames has been exposed. After the last frame in the row has been exposed, the movable frame is automatically returned to its original position such that the first exposed frame is once again located in position for exposure. The movable frame is then automatically indexed one position longitudinally so that the first frame in the next row is located in position for exposure. For an example of this type of camera reference may be had to U.S. Pat. No. 3,680,461.
While the type of camera shown in the abovementioned patent may be suitable for its intended purpose, i.e., recording large amounts of information in a very limited space, it does have its disadvantages. For example, the rather large movable frame must be indexed or shifted after each exposure therefore requiring a rather complicated and costly apparatus for indexing the movable frame. Further adding to the complexity and cost of the indexing apparatus is the fact that it must be capable of shifting the movable frame longitudinally as well as laterally. Another disadvantage to the above described camera is its lack of portability, i.e., it does not readily lend itself to being hand carried so that the user thereof could take a multiple of street scenes on a single sheet of film.
Another example of photographic apparatus of the type described is shown in U.S. Pat. No. 2,497,559. This patent describes a multiple exposure camera of the type which also includes a movable frame for supporting a film-holder in position for the exposure of a first predetermined portion of the film supported by the film-holder. After the first predetermined portion has been exposed, a spring wound motor automatically indexes the movable frame one step in a longitudinal direction to bring a second predetermined portion of the film into position for exposure. Subsequent to the exposure of the second predetermined portion, the motor indexes the movable frame one step in a lateral direction to bring a third predetermined portion of the film into exposure. The third predetermined portion of the film is exposed and the motor is again actuated to index the movable frame one step in a longitudinal direction, generally opposite to the first mentioned longitudinal direction, to bring a fourth and final predetermined portion of the film into position for exposure. After the fourth predetermined portion of the film has been exposed, the movable frame is indexed one step in a lateral direction, generally opposite to the first mentioned lateral direction, to return the movable frame to its original position.
Although the above-described multiple exposure camera may be particularly suited for use in a situation where the size of the camera is generally of no consequence, e.g., in portrait photography, it does not readily lend itself to application in a small, inexpensive, compact camera of the type which is adapted to be hand carried. The apparatus for indexing the movable frame after every exposure is relatively complex and together with the movable frame occupies a great amount of space in that the chamber in which the movable frame is mounted must be fifty percent longer and fifty percent wider than the length and width, respectively, of the movable frame.
Another problem associated with cameras of the type shown and described in the aforementioned patents is that the users of the cameras do not know for certain what results each exposure will produce until the exposed film has been removed from the camera, sent to a laboratory for development and then, hopefully, returned to the user. This problem has been solved in part by cameras of the type shown in U.S. Pat. Nos. 3,726,198 and 3,796,485. The first of these two patents shows and describes a camera of the self-developing type which is adapted to receive a camera back having a supply of pack film therein, the pack film preferably being of the type designated 108, manufactured by Polaroid Corporation, Cambridge, Mass. The camera back and its associated pack of film is mounted on the back of the camera such that one half of the film is located in position for exposure. Subsequent to the exposure of the first half of the film, the camera back is manually moved so as to locate the other half of the film in position for exposure. After the second half of the film has been exposed, the camera back is returned to its original position and the operator pulls a tab connected to the exposed film so as to position the film for travel between a pair of pressure applying members. The film is then drawn between the pressure applying members so as to enable them to rupture a pod of processing liquid and spread its contents across the exposed surface of the film to initiate the formation of a visible image in a superposed image-receiving sheet, as is well known in the art. The camera shown and described in U.S. Pat. No. 3,796,485 is similar to that just described except that its optical system comprises a twin lens system and circuit which selectively provides for the simultaneous or sequential operation of the twin lens system. This arrangement can form an image in each of two side by side portions of one area of a sheet of film which is one half of the available area of the film sheet when the twin lens system is programmed for sequential operation thus enabling a total of four separate exposures to be made on the film sheet. Alternatively, when the twin lens system is programmed for simultaneous operation, one half of the film sheet is exposed and then the camera back is moved to locate the other half of the film sheet in position for sequential or simultaneous exposure. However, as in the previously described self-developing type camera, the camera back must be manually moved between operations to reposition the film sheet.